This invention is concerned with an aqueous composition. More particularly, the present invention concerns an aqueous composition comprising, dispersed or dissolved therein, a copolymer of a terminally unsaturated oligomer.
Aqueous based coatings, such as for example latex or emulsion polymer containing paints, constitute a significant segment of all coatings in use today. Aqueous based coatings offer the advantages of being generally easier to use than conventional oil based coatings, such as for example alkyd paints, and contain fewer or no undesirable volatile organic solvents.
Formulators of aqueous based coatings desire to match or improve upon the performance properties of alkyd based paints, including for example scrub resistance, corrosion resistance, efflorescence resistance, block resistance, dirt pick-up resistance, tack resistance. mar resistance, print resistance. stress resistance and opacifying capability, Though it may be highly desirable for a paint to demonstrate maximum performance for all relevant properties, in reality such paints cannot be achieved, for example a paint with maximum dirt pick-up resistance may not be able to demonstrate maximum stress resistance as well. Instead, formulators tend to provide no optimized paints, which are paints having a compromise of several desirable properties, for example a paint with good dirt pick-up resistance may be able to demonstrate average stress resistance.
A formulator can alter the properties of a particular coating by adjusting it""s composition, such as by changing the particular amounts of the components and/or by changing the composition of those components.
Aqueous dispersions or solutions of carboxylic acid containing polymers are known to have many applications, including use as binders in coating compositions. Typically, these polymers are formed from the polymerization of a mixture of ethylenically unsaturated monomers comprising up to 20%, typically 0.05% to 10%, by weight of a carboxylic acid containing monomer, such as acrylic acid (AA) or methacrylic acid (MAA). The properties of a coating comprising such polymers can be altered by either changing the mixture of monomers to be polymerized to form a particular polymer, and/or by using two or more different polymers and/or by using multi-staged (e.g. core/shell) polymers, as disclosed for example in U.S. Pat. No. 4,193,902, EP-A-0466409, EP-A-0612805, EP-A-0694564 and EP-A-0741173.
WO-A-9532228 and WO-A-9532255 each disclose aqueous coatings including a binder based on a graft copolymer comprising 2 to 98%, preferably 60 to 95%, most preferably 60 to 85%, by weight of a polymeric backbone of polymerized ethylenically unsaturated monomers and 98 to 2%, preferably 40 to 5%, most preferably 40 to 15%, by weight of macromonomers attached to said polymeric backbone at a single terminal point of said macromonomer, said macromonomer having a number average molecular is weight of 500 to 30,000 and comprising 5 to 100%, preferably at least 10% and more preferable 20 to 40%, by weight of macromonomers, of polymerized alpha-beta ethylenically unsaturated monomers having carboxylic-acid functionalities or instead amine functionalities, and wherein at least a portion of the carboxylic-acid or amine groups have been neutralized and wherein the macromonomers are soluble or dispersed in aqueous carrier to stabilize the portion of the graft polymer which forms an insoluble particle. The graft copolymer is disclosed to have a weight average molecular weight up to 500,000, with a most preferred weight average molecular weight substantially less than 500,000 e.g. up to 300,000. The graft copolymers are described to be useful as film forming vehicles in the preparation of waterborne coating compositions such as, for example, basecoat or clearcoat compositions useful in automotive applications.
There is a continuing desire by formulators to provide aqueous coatings which demonstrate improved performance, such as scrub resistance, corrosion resistance, and/or efflorescence resistance, over other aqueous coatings. It is an object of this invention, therefore, to provide aqueous compositions which are particularly, though not exclusively, useful as performance enhancing binders for aqueous coatings. In particular, though not exclusively, it is the object of this invention to provide aqueous coatings for improving at least one of the following properties of an aqueous coating: scrub resistance, corrosion resistance, efflorescence resistance and opacifying capacity.
In accordance with the present invention, there is provided an aqueous composition comprising, dispersed or dissolved therein, a copolymer formed by polymerisation, preferably by emulsion polymerisation, of a monomer mixture consisting of:
a) 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: 
wherein N is the residue of an ethylenically unsaturated monomer of the formula: 
wherein M is the residue of an ethylenically unsaturated monomer other than N;
wherein said N and M residues are randomly arranged in said oligomer;
wherein m is the total number of M residues in said oligomer and is in the range 0 to 75;
wherein n is the total number of N residues in said oligomer and is in the range 3 to 150;
wherein n is equal to or greater than m and the sum of n and m is in the range from 3 to 150;
wherein X and each Y is independently selected from the group consisting of H, NH4, alkali metals and alkaline earth metals; and
wherein each Z is independently selected from the group consisting of H and CH3;
b) greater than 85.5 to 99.95% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing from 1 to 20 carbons, vinyl-aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides, and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and
c) 0 or up to 10% by weight of one or more other copolymerisable monomers.
In accordance with another aspect of the present invention, there is provided a method of improving the performance of a coating, wherein the method comprises I) applying to a substrate an aqueous coating composition comprising, dispersed or dissolved therein. a copolymer formed by polymerization, preferably emulsion polymerization, of a monomer mixture consisting of:
a) 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: 
wherein N is the residue of an ethylenically unsaturated monomer of the formula: 
wherein M is the residue of an ethylenically unsaturated monomer other than N;
wherein said N and M residues are randomly arranged in said oligomer;
wherein m is the total number of M residues in said oligomer and is in the range 0 to 75;
wherein n is the total number of N residues in said oligomer and is in the range 3 to 150;
wherein n is equal to or greater than in and the sum of n and in is in the range from 3 to 150;
wherein X and each Y is independently selected from the group consisting of H, NH4, alkali metals and alkaline earth metals; and
wherein each Z is independently selected from the group consisting of H and CH3;
b) greater than 85.5 to 99.95% by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing from 1 to 20 carbons, vinyl-aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and
c) 0 or up to 10% by weight of one or more other copolymerisable monomers; and II) drying the aqueous coating composition to form said coating.
Surprisingly, coatings formed from aqueous coating compositions comprising the aqueous composition defined above can demonstrate superior performance not only over coatings formed from conventional aqueous coating compositions based on copolymers which do not comprise an oligomeric component but also over those formed from aqueous coating compositions based on copolymers comprising higher quantities of oligomeric component (macromonomer).
The term xe2x80x9csaid N and M residues are arranged randomly in said oligomerxe2x80x9d as used in the definition of the terminally unsaturated oligomers a) means that the residue adjacent the terminally unsaturated moiety may be either an N or an M residue, that the residue adjacent to the residue adjacent the terminally unsaturated moiety may be either an N or an M residue, and so on.
Terminally unsaturated oligomers a) are known in the art. Processes suitable for the manufacture of oligomers a) are described, for example, in U.S. Pat. No. 4,056,559, U.S. Pat. No. 5,710,227, U.S. Pat. No. 5,587,431, U.S. Pat. No. 4,680,352, U.S. Pat. No. 4,694,054, and EP-0779305.
In the terminally unsaturated oligomers a) X is preferably H.
In the terminally unsaturated oligomers a) Y is preferably H.
In the terminally unsaturated oligomers a) Z is preferably H.
In the terminally unsaturated oligomers a) M is preferably a residue of the formula 
where X1 is xe2x80x94H or xe2x80x94CH3,
R is a phenyl radical, a vinyl radical, xe2x80x94CONH2, xe2x80x94CN or xe2x80x94COOX2,
X2 is H, a (C1 to C8) alkyl radical, a vinyl radical, or an allyl radical. More preferably, M is a residue of one or more ethylenically unsaturated monomers selected from the group consisting of methylacrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, styrene, isoprene, butadiene, vinyl acetate, acrylamide, acrylonitrile, allylmethacrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate.
In the terminally unsaturated oligomers a). the ratio of n:m is preferably in the range of 1:0 to 3:1. more preferably 1:0 to 9:1. Most preferably, the ratio of n:m is 1:0.
In the terminally unsaturated oligomers a) m is preferably in the range 0 to 9 and n is preferably in the range 3 to 50. More preferably, m is 0 and n is in the range 3 to 25.
Suitable monomers b) are (C1 to C24) alkyl (meth)acrylates, preferably (C1-C8) alkyl (meth)acrylates, most preferably methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl acrylate, butyl methacrylate and 2-ethylhexyl acrylate. The amides of acrylic and methacrylic acid is preferably acrylamide. The vinyl esters of carboxylic acids with from 1 to 20 carbons are preferably vinyl laurate, vinyl stearate, vinyl propionate and vinyl acetate, most preferably vinyl acetate. The vinyl aromatic compounds containing up to 20 carbons are preferably vinyltoluene, styrene, methylstyrene, butylstyrene and decylstyrene, most preferably styrene. The ethylenically unsaturated nitrites containing from 3 to 6 carbons are preferably acrylonitrile and methacrylonitrile. The vinyl halides are preferably vinyl chloride and vinylidene chloride. The non-aromatic hydrocarbons with 2 to 8 carbons and at least one olefinic double bond are preferably butadiene, isoprene and chloroprene.
Monomers b) are preferably selected from the group consisting of methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, decyl(meth)acrylate, lauryl(meth)acrylate, isobornyl(meth)acrylate, isodecyl(meth)acrylate, oleyl(meth)acrylate, palmityl(meth)acrylate, steryl(meth)acrylate, styrene, butadiene, vinyl acetate. vinyl chloride, vinylidene chloride, acrylonitrile, methacrylonitrile, acrylamide and glycidylmethacrylate.
The monomer mixture which is polymerized to form the copolymer optionally comprises up to 10% by weight of other copolymerisable monomers c). Suitable other copolymerisable monomers are preferably selected from the group consisting of hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mono-methyl itaconate, mono-methyl fumarate, monobutyl fumarate, maleic anhydride, phospho-ethyl methacrylate, glycidyl (meth)acrylates, substituted acrylamides, diacetone acrylamide, glycidyl (meth)acrylates, glycidyl methacrylate, acetoacetoxy ethyl methacrylate, acrolein, methacrolein, dicyclopentadienyl methacrylate, dimethyl meta-isopropenyl benzyl isocyanate, isocyanato ethyl methacrylate, methyl cellulose, hydroxyethyl cellulose, ethylene, propylene, N-vinyl pyrrolidone, N,Nxe2x80x2-dimethylamino(meth)acrylate, and polymerizable surfactants, including for example but not limited to Trem LF-40 available from Henkel Corp.
Preferably the copolymers have a weight average molecular weight above 500,000, more preferably above 750,000, and most preferably above 1,000,000, as measured by gel permeation chromatography.
Preferably the copolymers have a glass transition temperature (Tg) in the range of from xe2x88x9210 to 120 xc2x0 C., preferably xe2x88x925 to 40 xc2x0 C., as measured by Differential Scanning Calorimetry.
The monomer mixture which is polymerized to form the copolymer preferably comprises from 0.1 to less than 4.5%, more preferably from 1.0 to less than 4.5% by weight said terminally unsaturated oligomers a). Said monomer mixture preferably comprises 4% or less, more preferably 3% or less, and yet more preferably 2% or less, by weight of terminally unsaturated oligomer a).
The monomer mixture which is polymerized to form the copolymer preferably comprises more than 95.5%, more preferably 96% or more, more preferably 97% or more, and vet more preferably 98% or more, by weight of monomer b).
The above copolymer is preferably a latex wherein the particles of the dispersion preferably have an average diameter no greater than 250 nm, more preferably no greater than 150 nm, and most preferably no greater than 125 nm. In one embodiment of the present invention, the particles of the dispersion have an average diameter no greater than 100 nm.
The above copolymer dispersion may be formed by any emulsion polymerisation technique suitable for emulsion polymerisation of monomer mixtures comprising less than 4.5% by weight mono- or di- carboxylic acid monomer. Such techniques are well known in the art. For example, the emulsion polymerisation process described in U.S. Pat. No. 5,356,968 is very suitable for the preparation of the polymer dispersions of the present invention.
The copolymer dispersions according to the present invention can be used in the preparation of aqueous dispersions having a multimodal, e.g. bimodal, particle size distribution. Accordingly, in a further aspect of the present invention, there is provided an aqueous composition comprising a dispersion of polymer particles having a multimodal particle size distribution, wherein at least one mode of said multimodal particle size distribution is attributable to a dispersion of polymer particles comprising a copolymer formed by the emulsion polymerisation of a monomer mixture comprising:
a) 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: 
wherein N is the residue of an ethylenically unsaturated monomer of the formula: 
wherein M is the residue of an ethvlenicallv unsaturated monomer other than N;
wherein said N and M residues are randomly arranged in said oligomer;
wherein m is the total number of M residues in said oligomer and is in the range 0 to 75;
wherein n is the total number of N residues in said oligomer, and is in the range 3 to 150;
wherein n is equal to or greater than m and the sum of n and m is in the range from 3 to 150;
wherein X and each Y is independently selected from the group consisting of H, NH4, alkali metals and alkaline earth metals; and
wherein each Z is independently selected from the group consisting of H and CH3;
b) greater than 85.5 to 99.95% by weight of one or more monomers selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing from 1 to 20 carbons, vinyl-aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitriles containing from 3 to 6 carbons, vinyl halides, and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond: and
c) 0 or up to 10% by weight of one or more other copolymerisable monomers. Preferably, at least one mode of the multi-modal particle size distribution is attributable to a dispersion of polymer particles having an average particle diameter of from 40 to 150 nm. Preferably, a major portion of polymer particles within said at least one mode having an average particle diameter of from 40 to 150 nm are particles of said copolymer. In one particular embodiment, at least one mode of the multi-modal particle size distribution is attributable to a dispersion of polymer particles having an average particle diameter of from 40 to 100 nm. of which a major portion of polymer particles within said at least one mode are particles of said copolymer.
The aqueous dispersion having a multi-modal particle size distribution may be bimodal, or it may comprise more than two modes. The preparation and use of multi-modal emulsion polymers is well known in the art, for example as disclosed in U.S. Pat. No. 4,539,361 and U.S. Pat. No. 5,624,992.
Aqueous dispersions of the present invention may be prepared with high polymer solids content. For example, an aqueous dispersion of the present invention comprising polymer particles having a multi-modal particle size distribution may comprise 70% or more, e.g. up to 75%, by weight polymer solids. Accordingly, the aqueous dispersions of the present invention preferably comprise from 40 to 75% by weight polymer solids, more preferably 55 to 75% by weight polymer solids.
The aqueous compositions may be used in or as coatings, such as paints, primers and varnishes, binders for nonwovens and textiles, electronic chemicals, powder coatings, dispersants such as pigment dispersants, paper coatings, metal coatings, leather treatments, adhesives, floor polishes, caulks, and elastomeric wall mastics. The dispersions may be used alone or in combination with one or more other polymer dispersions.
Preferably, the aqueous compositions are used in paints to improve their performance properties. For example, the aqueous compositions of the present invention are useful for improving the scrub resistance of a coating, the corrosion resistance of a coating, the opacifying capacity of a coating, and/or the efflorescence resistance of a coating.
The aqueous compositions of the present invention are preferably used in or as architectural coatings such as interior and exterior house paints, including masonry paints, wood coatings and treatments, floor polishes, maintenance coatings such as coatings onto metal substrates, and traffic paints such as those paints used to mark roads, pavements and runways. In a preferred embodiment, the present invention includes a method for coating a substrate, wherein the substrate is a wall, floor or ceiling of a building.
In addition to the copolymer, the aqueous compositions of the present invention may include other optional components. Such other optional components include, without limitation, other polymers, surfactants, extenders, pigments and dyes, pearlescents, adhesion promoters, crosslinkers, dispersants, defoamers, leveling agents, optical brighteners, uv stabilizers, coalescents, rheology modifiers and antioxidants.
In a preferred embodiment, the present invention provides an aqueous composition comprising, dispersed or dissolved therein, I) a copolymer formed by polymerisation, preferably by emulsion polymerisation, of a monomer mixture consisting of:
a) 0.05 to less than 4.5% by weight of one or more terminally unsaturated oligomers of the formula: 
wherein N the residue of an ethyieriically unsaturated monomer of the formula: 
wherein M is the residue of an ethylenically unsaturated monomer other than N;
wherein said N and M residues are randomly arranged in said oligomer;
wherein m is the total number of M residues in said oligomer and is in the range 0 to 75;
wherein n is the total number of N residues in said oligomer and is in the range 3 to 150;
wherein n is equal to or greater than m and the sum of n and m is in the range from 3 to 150:
wherein X and each Y is independently selected from the group consisting of H, NH4, alkali metals and alkaline earth metals; and
wherein each Z is independently selected from the group consisting of H and CH3;
b) greater than 85.5 to 99.5 by weight of at least one monomer selected from the group consisting of esters of acrylic and methacrylic acid with alcohols containing from 1 to 24 carbons, amides of acrylic and methacrylic acid, vinyl esters of carboxylic acids containing from 1 to 20 carbons, vinyl-aromatic compounds containing compounds containing up to 20 carbons, ethylenically unsaturated nitrites containing from 3 to 6 carbons, vinyl halides, and non-aromatic hydrocarbons containing from 2 to 8 carbons and at least one olefinic double bond; and
c) 0 or up to 10% by weight of one or more other copolymerisable monomers; and II) an inorganic particulate material. Preferably the inorganic particulate material is selected from the group consisting of pigments, extenders and other inorganic particulate materials used in paints and primer compositions. Examples of such inorganic particulate materials include for example titanium dioxide, clays carbonates, and silicates. The preferred inorganic pigment is titanium dioxide. In this particular embodiment. the ratio of component I) to component II) is preferably in the range 1:10 to 10:1. Such compositions are particularly suitable for use in or as paints, undercoats or primers.
The invention will now be more specifically described in terms of the following examples of some preferred embodiments which are given for the purposes of illustration only, and may be contrasted with the comparative tests also given below.